(a) Field of the invention
The present invention relates to a cassette tape reel for video cassette tapes and the like and, more particularly, to a cassette tape reel which is characterized by its tape locking means.
(b) Description of the prior art
Known tape reels for video cassette tapes have locking means for fastening the tape to the reel as described below. As shown in FIG. 1, a cut portion 4 having the shape shown in the figure is formed in a hub 3 of tape reel 2. An end of tape 1 is put into the cut portion 4 and, then, a tape locking piece 5 is pushed into the cut portion 4 so that the tape 1 is fastened to the hub 3. In case of the above-mentioned tape locking means of known tape reel, a force in the direction shown by an arrowhead B in FIG. 1 is applied to a tape locking portion 5a of the tape locking piece 5 when the tape 1 is pulled in the direction shown by the arrowhead A. Because of the above-mentioned force, the tape locking piece 5 flexes and the tape locking portion 5a moves toward the direction shown by the arrowhead B. As a result, the tape locking piece 5 easily comes off from the cut portion 4. Moreover, in case of the above-mentioned tape locking means, the tape locking piece 5 is slightly deflected and the tape is fastened by the reaction caused by deflection. Therefore, it is difficult to make the curvature of circumferential surface 5b of tape locking piece 5 equal to the curvature of circumferential surface of hub 3 when the tape locking piece 5 is pushed into the cut portion 4.
FIG. 2 shows a known tape locking means chiefly used for hubs of audiotape cassettes in which a cut portion 7 is formed in a hub 6 and a locking pin 8 is pushed into the cut portion 7 to fasten the tape. In case of this tape locking means, tension in the direction shown by the arrowhead A occurs when the fastened tape is pulled and, as a result, the locking pin 8 will come off from the cut portion 7. This disadvantage can be eliminated when the entrance portion 7a of cut portion 7 is made narrow. When, however, the entrance portion 7a is made narrow, an extremely strong force will be required when the locking pin 8 is pushed into the cut portion 7. As a result, a flaw will be caused to the tape when fastening it and the tape will tend to break easily.
FIG. 3 shows another example of known tape locking means. This tape locking means is arranged to fasten the tape by using a tape locking piece 8' which is so constructed that a tape locking member 8'a corresponding to the locking pin 8 shown in FIG. 2 is connected to a hub 6' by a connecting member 8'b. That is, the tape is fastened by pushing the tape locking member 8'a of tape locking piece 8' into the cut portion 7'. This tape locking means also has the disadvantage, in the same way as the tape locking means shown in FIG. 2, that the tape locking piece easily comes off when the tape is pulled.